Candela Laser Corporation proposes the use of the flashlamp excited tunable dye laser for endarterectomy. This procedure could overcome limitations of current bypass surgery and balloon angioplasty of which approximately 700,000 procedures are performed annually. During Phase I, it was demonstrated that atherosclerotic plaque may be selectively and efficiently removed by tunable pulsed laser light. The first objective of Phase II is to examine the particulate matter generated during laser ablation. These studies will be carried out in collaboration with the Wellman Laboratory. Ablation will be conducted in an in vitro flow system supporting a cadaverous human artery. The particulates will be collected, measured and injected into swine to determine their clinical significance. The artery will be examined histologically to evaluate the condition of the vessel surface. For these studies, a unique high beam quality laser capable of generating pulses 10 - 50 us in duration, with energies up to 1 joule will be developed. The second main objective will be to design and test a fiber optic/catheter system to deliver the laser energy intravenously to the plaque. Our goal upon completion of Phase II is to have a laser/catheter system ready for clinical trials in human peripheral arteries.